Gas Turbine and Method For Shutting Off a Gas Turbine When Breakage of a Shaft is Identified

ABSTRACT

The invention relates to a gas turbine, especially an aircraft engine, with at least one compressor, at least one turbine and one combustion chamber, whereby fuel is supplyable to the combustion chamber by a fuel pump, and whereby upon identification of a break of a shaft, which couples a compressor with a turbine, the gas turbine can be shut off. According to the invention, at least one current conductor is arranged on the or each shaft, which current conductor is a component of a current supply for the fuel pump or a component of a current supply for a fuel pump regulation, whereby the integrity of the or each current conductor is monitored in such a manner that upon a change of the integrity of the or each current conductor the current supply of the fuel pump or of the fuel pump regulation is interrupted in order to automatically shut off the gas turbine.

The invention relates to a gas turbine according to the preamble of thepatent claim 1. Furthermore the invention relates to a method forshutting off a gas turbine upon identification of a shaft breakaccording to the preamble of patent claim 6.

Gas turbines, such as aircraft engines for example, comprise at leastone compressor and at least one turbine in addition to a combustionchamber. In gas turbines that comprise only a single compressor as wellas a single turbine, the compressor and the turbine are connected withone another by a single rotating shaft. If the gas turbine has twocompressors as well as two turbines, namely a low pressure compressor, ahigh pressure compressor, a high pressure turbine as well as a lowpressure turbine, then the low pressure compressor as well as the lowpressure turbine are connected with one another by a first shaft, andthe high pressure compressor as well as the high pressure turbine areconnected with one another by a second shaft. The two shafts thengenerally extend coaxially relative to one another, whereby one of thetwo shafts surrounds the other.

Overspeeding rotation conditions of a gas turbine as a result of a shaftbreak must be surely avoided. If a shaft break arises, then a compressorcoupled with the broken shaft will no longer take-up any power from thecorresponding turbine, whereby an overspeeding rotation of the turbineis caused. Because considerable damages can be caused on the gas turbineby the overspeeding rotation conditions, shaft breaks must be surelydetected or identified, in order to shut off the gas turbine as areaction thereto.

The DE 195 24 992 C1 discloses a method for regulating a shaft enginewith a micro-control device with monitoring of the engine for shaftbreak and overspeeding rotation. According to the method disclosedtherein, rotational speeds are measured with the aid of sensors, and theengine is tested with respect to shaft breakage and overspeedingrotation on the basis of these rotational speeds. If such an erroneousfunction is recognized, then the fuel delivery to the combustion chamberis interrupted and the gas turbine is deactivated.

In connection with the method disclosed in DE 195 24 992 C1, thedetermination of a difference rotational speed between a compressor-sideend or section and a turbine-side end or section of the gas turbineshaft is necessary. Accordingly, rotational speeds must be detected atat least two points, at a first compressor-side point and at a secondturbine-side point. Especially in the hot turbine area, a rotationalspeed determination requires complicated provisions, whereby carryingout the method known from the prior art has been shown to be expensiveand complicated. Furthermore, the method known from DE 195 24 992 C1 isonly applicable on one or two-shafted gas turbines. On the other hand,this method known from the prior art is not practicable formulti-shafted gas turbines. This especially applies to more thantwo-shafted gas turbines, because a shaft surrounded by rotating shaftscannot easily without further efforts be referenced to a stationaryreference system.

Beginning from this, the problem underlying the present invention is toprovide a novel gas turbine and a novel method for shutting off a gasturbine upon identification of a shaft break thereof.

This problem is solved by a gas turbine according to patent claim 1.According to the invention, at least one current conductor is arrangedon a shaft, whereby the current conductor is a component of a currentsupply for the fuel pump or a component of a current supply for a fuelpump regulation, whereby the integrity of the or each current conductoris monitored in such a manner that upon a change of the integrity of theor each current conductor, the current supply of the fuel pump or thecurrent supply of the fuel pump regulation is interrupted, in order toshut off the gas turbine in a self-acting or automatic manner.

A shaft break can be surely and easily detected in the inventive gasturbine. In comparison to the prior art, in the inventive gas turbine noseparate arrangement is necessary in order to shut off the gas turbineupon a shaft break. Rather, in the invention, the gas turbine can beshut off directly from the integrity monitoring of the or each currentconductor. This increases the reliability and reduces the costs.

The inventive method for shutting off a gas turbine upon identificationof a shaft break thereof is defined in the independent patent claim 6.

Preferred further developments of the invention arise from the dependentclaims and the following description.

In the simplest example embodiment of the present invention, a gasturbine is proposed, which has a compressor, a turbine and a combustionchamber, whereby the compressor and the turbine are connected with oneanother via a shaft, and whereby fuel is introduced into the combustionchamber via a fuel pump. Now, in order to shut off the gas turbine toavoid overspeeding rotation conditions upon the occurrence of a shaftbreak of the shaft that couples the compressor and the turbine with oneanother, in the sense of the present connection it is proposed toarrange at least one current conductor on the shaft. For an electricallydriven fuel pump, the current conductor is directly a component of acurrent supply for the fuel pump. For a mechanically driven fuel pump,to which a fuel pump regulation is allocated, the current conductor is acomponent of a current supply for the fuel pump regulation.

If now a shaft break arises, then the integrity of the or each currentconductor will also be changed, whereby upon a change of the integrityof the or each current conductor, the current supply of the fuel pump orthe fuel pump regulation will be automatically interrupted, in order toshut off the gas turbine. If the current conductor is a component of thecurrent supply of the fuel pump, then upon a shaft break and therewith abreak of the current conductor, the current supply of the fuel pump willbe directly interrupted. If the current conductor is a component of thecurrent supply of the fuel pump regulation, then upon a shaft break andtherewith a break of the current conductor, the fuel pump regulation isdirectly interrupted. In both cases, thereby the gas turbine can be shutoff directly, that is to say without a further device or arrangement.

It thus lies in the sense of the present invention to arrange, on atleast one shaft that is to be monitored, at least one electrical currentconductor that is a component of an electrical or current circuit. Ifthe or each electrical current conductor is damaged upon a shaft break,then the corresponding electrical or current circuit is interrupted andthe fuel supply to the combustion chamber can be directly shut-off. Fromthat there arises a simple as well as sure shutting-off of the gasturbine upon a shaft break.

At this point it is mentioned that the or each current conductorallocated to the rotating shaft can be arranged partially within as wellas partially outside of the shaft. Thus, the current conductors can beguided along either on an inner side or an outer side of the shaft.

The inventive principle is also applicable to multi-shaft gas turbinesin a simple manner. For this purpose, at least one current conductor isallocated to each shaft.

With the aid of the present invention, a sure determination of a shaftbreak is possible. As a result of that, structural assemblies of the gasturbine, for example the rotors, can be embodied narrower and lighter,which leads to weight savings on the one hand and cost savings on theother hand. Only relatively few components are necessary for determiningthe shaft break. The inventive system is compactly constructed anddetects a shaft break immediately and directly, without having to takefurther mechanisms into consideration. The invention can be embodied ina redundant manner with simple means. Simply the number of the currentconductors being utilized needs to be multiplied. A shaft break isdetectable in a simple and sure manner on multi-shaft gas turbines, andas a result the fuel supply to the combustion chamber can be directlyshut off.

1. Gas turbine, especially aircraft engine, with at least onecompressor, at least one turbine and one combustion chamber, wherebyfuel is supplyable to the combustion chamber by a fuel pump, and wherebythe gas turbine can be shut off upon identification of a break of ashaft that couples a compressor with a turbine, characterized in that atleast one current conductor is arranged on the or each shaft, wherebythe current conductor is a component of a current supply for the fuelpump or a component of a current supply for a fuel pump regulation,whereby the integrity of the or each current conductor is monitored insuch a manner that upon a change of the integrity of the or each currentconductor the current supply of the fuel pump or of the fuel pumpregulation is interrupted, in order to automatically shut off the gasturbine.
 2. Gas turbine according of claim 1, characterized in that theor each current conductor is a component of a current supply of the fuelpump, whereby upon a shaft break and therewith a break of the or eachcurrent conductor the current supply of the fuel pump is directlyinterrupted in order to automatically shut off the gas turbine.
 3. Gasturbine according to claim 2, characterized in that the fuel pump iselectrically driven.
 4. Gas turbine according to claim 1, characterizedin that the or each current conductor is a component of a current supplyof the fuel pump regulation, whereby upon a shaft break and therewithbreak of the or each current conductor, the fuel pump regulation isdirectly interrupted in order to automatically shut off the gas turbine.5. Gas turbine according to claim 4, characterized in that the fuel pumpis mechanically driven.
 6. Method for shutting off a gas turbine uponidentification of a shaft break of the gas turbine, characterized inthat the integrity of at least one current conductor that is allocatedto a shaft of the gas turbine and that is a component of a currentsupply for the fuel pump or a component of a current supply for a fuelpump regulation, is monitored in such a manner that the current supplyof the fuel pump or of the fuel pump regulation is interrupted based ona change of the integrity of the or each current conductor in order toautomatically shut off the gas turbine.
 7. Method according to claim 6,characterized in that the integrity of at least one current conductorthat is a component of a current supply of the fuel pump is monitored,whereby upon a shaft break and therewith a break of the or each currentconductor the current supply of the fuel pump is directly interrupted inorder to shut off the gas turbine.
 8. Method according to claim 6,characterized in that the integrity of at least one current conductorthat is a component of a current supply of the fuel pump regulation ismonitored, whereby upon a shaft break and therewith a break of the oreach current conductor, the current supply of the fuel pump regulationis directly interrupted in order to shut off the gas turbine.